The present invention relates to reaction flavors and more specifically to reaction flavors suitable for use in smoking products. The invention is also concerned with processes for preparing the reaction flavors and their subsequent incorporation into smoking compositions and particularly reconstituted tobacco.
The increased demand for low delivery smoking products has necessitated a need for redesigning flavor systems compatible with these products. Low delivery smoking products are generally designed to deliver 15 mg of tar or less. Tar is generally defined as the total particulate matter (TPM) that is collected on a Cambridge filter minus the nicotine and water content. Manufacture of low delivery products is generally achieved by use of highly efficient ventilated filters, porous wrappers, modified tobacco blends, and the like. The use of porous wrappers and/or ventilated filters results in considerable air dilution of the smoke with a concomitant dilution of flavorants entrained in the smoke. In order to overcome the problem of "flavor dilution" new systems for flavor incorporation are required.
It is generally recognized that simply adding additional amounts of individual flavorants is not feasible in that pronounced "pack aroma" usually results. Moreover, addition of excessive flavorants to smoking materials may result in increased density of the materials and a decrease in the filling capacity thereof. A flavor system for low delivery cigarettes having increased impact and "full body" is therefore desirable to overcome the presently recognized problems. Since reconstituted tobacco is an ideal filler for low delivery cigarettes, it is of utmost importance that flavor systems be designed that are capable of overcoming the "stemmy" taste generally associated with some reconstituted tobaccos. Moreover, it is necessary to design a system wherein the flavorants may be added in extremely low amounts and still maintain the desired flavor level and physical characteristics described above.
The reaction of sugars and amino acids to produce desirable flavorants for smoking materials has generated increased interest. For example, U.S. Pat. No. 3,478,015 describes "browning reactions" in which an amino acid and a sugar having an active carbonyl are reacted in a lower alkyl polyhydric alcohol solvent in the absence of water at a temperature less than 90.degree. C. for about 5 to 15 hours. The resultant reaction mixture is applied in an amount of about 1% by weight to tobacco.
U.S. Pat. No. 3,920,026 describes tobacco flavorants prepared by reacting valine with a carbonyl compound selected from sugars, dihydroxy acetone, or pyruvaldehyde. The reaction takes place in a solvent such as glycerol or propylene glycol and at a temperature between about 120.degree. and 200.degree. C., and preferably at about 150.degree. to 160.degree. C. for 0.5 to 5 hours depending on the type of sugar used. Flavanoid catalysts, such as quercetin or rutin or a hydroxyacid such as ascorbic acid, may be used. The reaction mixture may be applied directly on tobacco or may be fractionated to separate the volatile and nonvolatile fractions, which are then used as tobacco flavorants.
U.S. Pat. No. 3,722,516 discloses the addition of dihydroxyacetone alone or in combination with amino acids to enhance the natural flavor characteristics of tobacco, and especially the caramel-like or burned sugar-like aroma thereof.
Japanese Pat. No. 9239/71 discloses certain tobacco "perfumes" such as 1-deoxy-1-L-prolino-D-fructose, which is a sugar-amino acid condensation product. This compound, as well as others, are prepared by reacting an amino acid with a sugar in an aqueous or alcohol solvent, and usually in the presence of an acid catalyst such as malonic acid. The desired compounds may be separated and purified by the use of ion-exchange resins and are thereafter applied to tobacco.
Japanese Pat. No. 3398/73 discloses certain other specific amino acid-sugars such as 1-deoxy-1-L-alanino-D-fructose that are synthesized from their respective components by the Amadori rearrangement, in the presence of malic acid as catalyst, by heating at 130.degree. C. for 15 minutes. The specific compounds are isolated and may be combined with cocoa to produce tobacco flavorants.
Two articles by Koehler (Journal of Agricultural Food Chemistry, Volume 17, Number 2, pages 393-396, 1969 and ibid., Volume 18, Number 5, pages 895-898, 1970) discuss pyrazine formation in sugar-amino acid model systems. The normal model system consisted of asparagine and glucose reactants in a 1 to 1 molar ratio. Diethylene glycol solvent and a small amount of water were also used. The mixture was heated for 24 hours at 120.degree. C. The use of a base catalyst, such as sodium hydroxide or ammonium hydroxide, resulted in an increase in the production of volatile alkylated pyrazines. In some instances, the addition of an aldehyde, such as acetaldehyde, appeared to increase pyrazine formation. Koehler's work was related to browning reactions known to occur in foods such as roasted peanuts, coffee, cocoa, and potato chips; and has primary object was to determine the chemical factors involved in volatile pyrazine formation during these reactions. Although volatile pyrazines were isolated and identified, there is no suggestion by Koehler that his reaction mixture would be suitable for use as a tobacco flavorant.